Interpretive Summary: Nanotechnology has the potential to revolutionize agricultural and food system, especially in food industry with various applications including food safety, quality, product traceability, better nutrient delivery system, enhancing packaging performance, and improving food processing. With the development in nanotechnology, nanobiosensors for detecting food toxin can be very important in food safety and biosecurity. Among many different food toxins, ricin is a poison that can be made from the waste left over from processing castor beans. The Center for Disease Control (CDC) categorized ricin as category B toxins that are moderately easy to disseminate. Because food toxins can be effective in very low doses to human, the detection systems need to have high sensitivity, specificity and speed. However, current technologies do not meet all these requirements. In this paper, a new method to detect food toxin at the nano and sub-nano scale (single molecule level) and specifically (using single molecule interaction recognition) with AFM-based fast single-molecule interaction recognition system will be presented. The methodologies and protocol demonstrated in this presentation can be used for fast detection of other biological agents and toxins in food as well as biosecurity, and clinical diagnostics with high sensitivity and specificity.